Local Anesthesia for Dental Professionals - Vasoconstrictors

1. Based on Text- Local Anesthesia for Dental Professionals
1st ed. Dr. StanleyMalamed 2nd ed. Bassett, DiMarco,
Naughton
Local Anesthesia for Dental Professionals

3.  LA are vasodilators
 Dilation results in
 Increased rate of absorption of LA into CV system
 Removes drug
 Higher plasma levels of LA
 Increased risk of toxicity
 Decrease in depth and duration of LA
 Diffusion away from site and redistribution
 Increased bleeding at site of treatment

5.  Decrease blood flow – perfusion to site
 Slows absorption of LA into CV system
 Blood levels of LA are lowered
 Increase in LA concentration gradient into nerve
 Decreased bleeding at site of administration

6.  Chemically identical or similar to
 Sympathetic nervous system mediators
(neurotransmitters)
 Epinephrine & Norepinephrine
 Classification
 Sympathomimetic or Adrenergic

8.  Chemical structure related to catechol nucleus
 If an amine group is attached to aliphatic side
 Classified as catecholeamine
 Naturally occurring Catecholamines
 of Sympathetic System
 Epinephrine
 Norepinephrine
 Dopamine
 Synthetic Catecholamies
 Isoproterenol & levonordefrin

9. Catecholamines
 Epinephrine
 Norepinephrine
 Dopamine
 Levonordefrine
 Isoproterenol
 Amphetamine
 Methamphetamine
 Ephedrine
 Methentermine
 Hydroxyamphetamine
 Metaraminol
 Methoxamine
 Phenylephrine
Noncatecholamines

10.  Direct acting
 Act directly on adrenergic receptors
 Indirect acting
 Acts by releasing norepinephrine from adrenergic nerve
terminals
 Mixed acting
 Both directly on receptors and release of norepinephrine

11.  Found in most tissues of body
 Alpha and Beta receptors
 Inhibitory or excitatory

12.  Alpha receptors
 Activated by sympathomimetic drug
 Vasoconstriction
 Contraction of smooth muscle in blood vessel
 Alpha 1 excitatory postsynaptic
 Alpha 2 inhibitory postsynaptic

15.  Beta Receptors
 Beta 1 - Found in heart and intestines
 Cardiac stimulation and lipolysis
 Increased heart rate and strength of contraction
 Beta 2 - Found in bronchi, vascular beds, uterus
 Bronchodilation and vasodilation

16.  Amphetamine or tyramine
 Act indirectly
 Causes release of norepinephrine from storage in
nerve terminals
 Action is that of the released norepinephrine
 Repeated doses of drug is less effective due to
depletion of norepinephrine
 Called Tachyphylaxsis
 Only seen with indirect acting drugs

17.  Ratio of drug to carrier medium
 1:1000 = 1 g or 1000 mg of solute (drug)
 to 1000 mL of solution
 1:1000 contains 1000 mg in 1000 ml
 1:10,000 contains .1 mg/mL
 1:100,000 contains .01 mg/mL
1:100,000 xylo 2% w / epi - .01mg/ml x 1.8 ml = .018 mg epi

18.  Used to prolong the duration of LA
 1:200,000 epi contains .005mg/mL epi
 provides comparable results with fewer systemic side effects
 Widely used and accepted in dentistry and medicine

19.  Resting plasma level
 Doubled after administration
 of one carpule of 1:100,000 epi
 Epinephrine levels equivalent to moderate to heavy
exercise occur after intraoral injection
 Associated with moderate increases in cardiac output and
stroke volume
 Blood pressure and heart rate are minimally affected

20.  Sympathomimetic reactions
 Apprehension
 Tachycardia
 Sweating
 Heart palpitation

21.  Intravascular injection
 Hyperresponders
 Increase in heart rate of
25 – 70 beats per minute
 Elevation in BP 2 to 70
mm HG
 Rhythm disturbances
 Premature ventricular
contractions (PVC’s)

23. Alpha 1 stimulation by epinephrine

24.  Lacks significant beta 2 activity
 Produces intense peripheral vasoconstriction
 Possible DRAMATIC elevation in BP
 Side effect ratio
 9 times higher than epinephrine

25. Acts on Alpha and Beta receptors
with Beta dominating

26.  Myocardium
 Beta 1 receptors stimulated
 Positive inotropic – force of contraction
 Positive chronotropic - Cardiac output and rate
increased
 Pacemaker cells
 Beta 1- increased irritability of cells
 Increased dysrrythmias

27.  Coronary Arteries
 Dilation of CA and increased blood flow
 Blood Pressure
 Systolic BP increased
 Large doses – diastolic increased due to systemic
constriction
 Caused by alpha receptor response

28.  CV dynamics
 Direct stimulation
 Increased systolic and diastolic BP
 Increased Cardiac Output
 stroke volume & heart rate increased
 Increased strength of contraction
 Increased myocardial demand for oxygen

29.  Vasculature
 Constriction due to alpha receptor stimulation
 Skin, mucous membranes, kidneys
 beta 2 receptors
 dilation
 alpha 1 receptors
 constriction

30.  Hemostasis
 Epi is used for vasoconstriction
 Predominant alpha 1 receptor action
 Beta receptors domination
 Reverts to dilation and increased bleeding
 Post op bleeding 6 hours after injection
 Respiratory System
 Potent dilator due to Beta 2 stimulation
 Bronchiolar smooth muscle relaxed
 Management of bronchospasm – status asthmaticus

31.  CNS
 Not a potent CNS stimulant
 Metabolism
 Epi increases oxygen consumption in all tissues
 Beta stimulation – glycongenolysis in liver and skeletal
muscle
 Elevates blood sugar
 Termination of action
 Reuptake in adrenergic nerves
 Inactivated in
 blood by COMT - catechol-O-methyltransferase
 In Liver - Hepatic system by MAO - monoamine oxidase

34.  Maximum dose
 1:100,ooo concentration recommended in USA
 Typical concentrations of epi in LA are not
contraindicated
 Aspiration is mandatory
 Inject slowly
 Smallest effective dose administered
 Maximum dose limited to .2 mg per appointment
 .018 mg/cartridge
.2 mg epi / .o18 mg/ carpule = 11 carpules

35.  Overdose
 CNS stimulation
 Increasing fear, tension
and anxiety
 Tension, tremors,
weakness
 Dizziness, palor,
palpitation and
respiratory difficulty

36.  Cardiovascular compromised patient
 Limit or avoid vasoconstrictors
 ASA 3 - 4 poorly controlled are greater risk
 Weigh risk to benefit
 Hemostasis
 Infiltration into site
 Minimize hemorrhage due to vasoconstriction
 Rebound effect due to beta predominating

37.  Neo-Cobefrin
 Used with mepivicaine –
carbocaine
 Mode of action thru
 direct alpha 75%
 and beta stimulation
25%
 15% as potent as
epinephrine

38.  CV dynamics = epi
 Vasculature = epi
 Termination of action and elimination
 COMT
 MAO
 Maximum dose = 1 mg per appointment
 15% as effective as epi so a higher concentration is used
 1:20:000 = .09 mg/cartridge
1 mg / .09 mg/carpule = 11 carpules

39.  Epinephrine - or – Levonordefrin ???
 Length of dental appointment
 Prolongs duration and depth of anesthesia
 Restorative for 50 minutes = may need epi or levo
 Requirement for hemostasis
 Vasoconstriction with rebound vasodilation
 Medical status of patient
 Risk / benefit must be evaluated

40.  Medical status of patient
 Risk / benefit must be evaluated
 ASA 3 – 4
 Thyroid disease
 Diabetes

41. Sulfite sensitivity
 Antioxidant to preserve
epi
 Acidifies the solution
increasing cations
 diffusion into axon is
slower
 Delayed onset of LA

43.  Trycyclic antidepressants
 Greater risk of dysrythmias
 Levonordefrin is contraindicated
 Norepinephrine is contraindicated
 Phenothiazines
 With epi may cause postural hypotension
 Non-selective beta blockers
 Beta blocked and alpha dominates
 Peripheral constriction (HTN ) and bradycardia

44.  Unstable diabetes
 Epi causes glycogenolysis
 hyperglycemia and ketoacidosis
 Unstable – active angina
 Epi stimulates beta receptors
 increasing cardiac rate and oxygen demand
 Recent MI / CABG
 Medical consult prior to care

45.  Severe HTN or untreated HTN
 Contraindicated if uncontrolled (over 170 systolic)
 Uncontrolled CHF
 The pump is simply failing and patient is a poor risk

46.  Slows rate of absorption
 Lowers systemic blood levels of LA
 Prolongs duration of LA
 Intensifies depth of LA
 Reduces systemic reactions